In a construction machine such as a hydraulic excavator, a diesel engine is mounted as a prime mover of a hydraulic pump; thus, the construction machine, like heavy trucks and motorcoaches, is equipped with an exhaust gas purification system for purifying nitrogen oxides (hereinafter, referred to as NOx) contained in exhaust gas from the engine. As such an exhaust gas purification system, there is known one configured such that an exhaust gas after-treatment device containing a reduction catalyst is installed in an exhaust pipe of the engine, an aqueous urea solution injection device is provided upstream of the reduction catalyst, an aqueous urea solution is injected from this aqueous urea solution injection device to generate ammonia in the exhaust gas, and a reduction reaction of NOx in the exhaust gas with ammonia on the reduction catalyst causes NOx to be decomposed into harmless water and nitrogen. An example of this system is disclosed in Patent Document 1.
Furthermore, in a construction machine such as a large hydraulic excavator, a fuel tank that stores a fuel is installed at a high position from the ground; thus, as disclosed in, for example, Patent Document 2, a refueling system for performing refueling from the ground is provided at a lower position than that of the fuel tank.